Description of the Related Art
Impotence in males is the consistent inability to achieve or sustain an erection of sufficient rigidity for sexual intercourse. Impotence is recognized to be an age-dependent disorder, and it has recently been estimated that at least 5% of 40-year-old men and between 15% and 25% of 65-year-old men experience erectile dysfunction on a long-term basis. In 1985 in the United States, impotence accounted for more than several hundred thousand outpatient visits to physicians, and in 1998 it was estimated that approximately 10 million American men were impotent. Depending on the nature and cause of the problem, treatments historically included psychosexual therapy, hormonal therapy, administration of vasodilators such as nitroglycerin and α-adrenergic blocking agents (“α-blockers-”), oral administration of other pharmaceutical agents, vascular surgery, implanted penile prostheses, vacuum constriction devices and external aids such as penile splints to support the penis or penile constricting rings to alter the flow of blood through the penis. More recently, orally administered selective Phosphodiesterase-5 (PDE-5) inhibitors, such as sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) have been approved for the treatment of erectile dysfunction, with additional drugs pending approval (i.e., udenafil and avanafil). These drugs selectively inhibit the action of PDE-5, which is cGMP-specific and responsible for the degradation of cGMP in the corpus cavernosum.
In healthy adult males, the process of penile erection and the subsequent return of the penis to the flaccid state involves a “delicate dance” within the male anatomy, which typically involves (1) dilation of the arteries that regulate blood flow to the lacunae of the corpora cavernosum to increase blood inflow, (2) relaxation of trabecular smooth muscle, which facilitates engorgement of the penis with blood, and (3) compression of the venules by the expanding trabecular walls to decrease venous outflow. Assuming no significant leakage of blood, when a greater amount of blood flows into the penis than out, engorgement of the penile tissues can occur—typically creating an erection. After an erection, when less blood flows in than out, engorgement of the penis can be reversed, with the flaccid state typically achieved.
A number of causes of impotence have been identified, including vasculogenic, neurogenic, endocrinologic and psychogenic. Vasculogenic impotence, which is caused by alterations in the flow of blood to and from the penis, is thought to be the most frequent organic cause of impotence. Common risk factors for vasculogenic impotence include hypertension, diabetes, cigarette smoking, pelvic trauma, and the like. Neurogenic impotence is associated with spinal-cord injury, multiple sclerosis, peripheral neuropathy caused by diabetes or alcoholism and severance of the autonomic nerve supply to the penis consequent to prostate surgery. Erectile dysfunction is also associated with disturbances in endocrine function resulting in low circulating testosterone levels and elevated prolactin levels.
Consequently, there are a considerable number of events and/or factors that may cause or enhance the effects of erectile dysfunction, and a corresponding array of medications and therapies to manage the symptoms of erectile dysfunction. However, there are few medications and/or therapies that seek to specifically target the etiology of erectile dysfunction, and none that prevent further impairment from the underlying causes of erectile dysfunction. For example, pharmacological treatment methods such as selective PDE-5 inhibitors have become increasingly popular for treatment of erectile dysfunction, but these drugs typically only “supplement” the naturally-occurring concentration and/or effects of proteins, enzymes and/or hormones on a temporary basis—they do nothing to address the underlying localized and/or systemic cause of the patient's erectile dysfunction. Moreover, there remains a significant proportion of the adult male population, which is estimated to range from 30% to 50% of ED sufferers, who experience little or no benefit from such drugs. In addition, there are a large number of individuals suffering from erectile dysfunction who take medications (for other serious medical conditions) incompatible with PDE-5 inhibitors, such as nitrate drugs or anticoagulant medications. There are many individuals who suffer from various medical conditions incompatible with PDE-5 inhibitors, such as heart disease or heart failure, strokes, uncontrolled high or low blood pressure, eye problems such as retinitis pigmentosa, severe liver disease and/or have kidney disease requiring dialysis. In addition, vasodilators only induce temporary erections following administration and do not address or treat the basic vascular/cavernosal pathology which may be causing erectile dysfunction, and there are many patients who would prefer a more permanent and/or “long-term solution” to their erectile dysfunction issues, rather than being required to ingest a medication on a frequent basis.
In addition, there are a number of sexual dysfunction issues resulting from abnormal vascular circulation that can affect females in a similar manner. Specific physiologic impairments of vasculogenic female sexual dysfunction can include vaginal engorgement and clitoral erectile insufficiency syndromes, which can include symptoms such as delayed vaginal engorgement, diminished vaginal lubrication, pain or discomfort with intercourse, diminished vaginal sensation, diminished vaginal orgasm, diminished clitoral sensation or diminished clitoral orgasm. In many cases, a root cause of such dysfunction issues could be an abnormality in the vascular physiologic processes in the affected individual(s), which might also be amendable to the various systems, devices and methods of treatment described herein.